Using "serial" to connect to an Arduino

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I got an Arduino for xmas, and I'm trying to talk to it from MATLAB (R2012a prerelease) via the serial interface. I'm not having any luck at the moment, I can talk to it from python no problem. Here's what I've got:
>> s = serial('/dev/ttyACM0', 'BaudRate', 9600);
>> fopen(s)
Error using serial/fopen (line 72)
Open failed: Port: /dev/ttyACM0 is not available. Available ports: /dev/ttyS0.
Use INSTRFIND to determine if other instrument objects are connected to the requested device.
But in ipython:
In [1]: import serial
In [2]: s = serial.Serial('/dev/ttyACM0', 9600)
In [3]: s.readline()
Out[3]: '408\r\n'
I've tried '/dev/ttyS0' and made sure I closed old connections, but I still get this error. I've run out of ideas, anyone have suggestions?
  1 Comment
Thomas Ibbotson
Thomas Ibbotson on 4 Jan 2012
Forgot to point out that I'm on 64-bit linux (Ubuntu 11.10)

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Accepted Answer

Thomas Ibbotson
Thomas Ibbotson on 5 Jan 2012
I found the following solution on the newsgroup:
Hi Patrick
You can use /dev/ttyACM0 but you need to let the library know that you will be using it. To specify the ports on your system, create a java.opts file in the directory you start MATLAB from with the following line in it:
After you restart MATLAB, the port should be found:
>> instrhwinfo('serial')
ans =
AvailableSerialPorts: {2x1 cell}
JarFileVersion: 'Version 2.7.0'
ObjectConstructorName: {2x1 cell}
SerialPorts: {2x1 cell}
>> ans.AvailableSerialPorts
ans =
Another option is to create a symbolic link from /dev/ttyS101 to
/dev/ttyACM0. The port should be enumerated as ttyS101 then.

More Answers (4)

Walter Roberson
Walter Roberson on 4 Jan 2012
Is ttyACM0 a virtual USB port? If so then the device needs to be connected when you start MATLAB, as MATLAB only scans the device table once.
  1 Comment
Thomas Ibbotson
Thomas Ibbotson on 4 Jan 2012
Yes, the device was connected when MATLAB started.

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Jan on 19 Apr 2012
i got the same problem. using ubuntu 11.10 and matlab 2010b with arduino ide 1.0
in which folder do i have to put the java.opts file?
/usr/local/MATLAB/R2010b/ ?
Thomas Ibbotson
Thomas Ibbotson on 19 Apr 2012
I assumed you're on 64-bit linux, if it's 32-bit then the directory will be glnx86. In any case you can find out from MATLAB which architecture you are using from the command:

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Jan on 19 Apr 2012
ok, thank you! it s working :)

Bagus Tris Atmaja
Bagus Tris Atmaja on 7 Feb 2015
I have same problem with Matlab 2013 in Ubuntu 14.04. When I try fnd info from serial port, it is live,
>> instrhwinfo('serial')
ans =
AvailableSerialPorts: {'/dev/ttyS101'}
JarFileVersion: 'Version 3.3'
ObjectConstructorName: {'serial('/dev/ttyS101');'}
SerialPorts: {'/dev/ttyS101'}
but, when I connect it with arduino (using ArduinoIO package),
>> a=arduino('/dev/ttyS101');
Attempting connection .............
Warning: Unsuccessful read: A timeout occurred before the Terminator was reached.
Error using arduino (line 104)
Connection unsuccessful, please make sure that the board is powered on, running a
sketch provided with the package, and connected to the indicated serial port. You
might also try to unplug and re-plug the USB cable before attempting a
Any idea? I guess the error from ArduioIO package

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